On-line process identification and PID controller autotuning

We propose a new and simple on-line process identification method for the a utomatic tuning of the PID controller. It does not require a special type o f test signal generators such as relay or P controller only if the signals are persistently exciting. That is, a user can choose arbitrary signal gene rators such as relay, a P controller, the controller itself, pulse signal a nd step signal generator because it needs only the measured process output and the controller output. It can incorporate nonlinearities due to actuato r saturation or manual mode operation during identification work and shows a good robustness to measurement noises, nonlinearity of the process and di sturbances. The proposed autotuner combined with the identification method and tuning rule using a model reduction shows good control properties compa red with previous autotuning methods.